Wurster coating of multi-particulates with polymer suspensions and solutions is widespread in the pharmaceutical industry. Several formulations for polymer coatings of aqueous dispersions and organic solvent based polymer systems require glidants such as talc, stearates, silica compounds, calcium compounds, and many other materials to be suspended into the polymer solutions to cut down on polymer tackiness and reduce agglomeration. These glidants can aggregate or may not be available as a fine enough particle to suspend indefinitely and so can fall out of solution during the process, causing spray gun plugging and line plugging. Plugging of the spray gun and lines normally requires shutdown of the machine for cleaning, which delays the coating process and increases the production costs. Adding glidant to a suspension or solution reduces the rate of polymer application by the very nature of the formulation, which typically requires the same amount of glidant to be in suspension as polymer. For a given application rate only half is polymer, leading to extended processing times and inefficient coating processes.
In the typical spray application where glidant is included in the suspension or solution, the glidant is necessarily coated with polymer as it is sprayed on to the substrate particle, reducing its ability to spread on to the substrate and is less effective in reducing aggregation.
Therefore, there is a need for an improved Wurster coating machine and process, which eliminates the problems in the prior art.
Accordingly, a primary objective of the present invention is the provision of a Wurster accelerator having a powder applicator with improved performance.
Another objective of the present invention is the provision of a Wurster accelerator which applies dry powder without plugging a spray gun or associated lines.
A further objective of the present invention is the provision of a Wurster coating machine which applies dry powder to the particles in the fluid bed without agglomeration or aggregation.
Still another objective of the present invention is the provision of a Wurster accelerator with a dry powder line connected to the accelerator sleeve to deliver dry powder to the particles in the fluid bed.
Yet another objective of the present invention is the provision of a process for coating particulate material with dry powder using a Wurster accelerator.
A further objective of the invention is to reduce suspension or solution preparation time and complexity in a Wurster coating processor.
A further objective is the provision of a Wurster dry powder coating process wherein the glidant it removed from the suspension or solution and applied as a dry substance, thereby increasing its efficient use and efficacy in reducing aggregation, compared to glidant that is in suspension and therefore coated with polymer as it is applied in the spray.
A further objective is the provision of a Wurster dry powder coating process which allows higher amounts of polymer in suspension or solution by eliminating the glidants in the suspensions or solutions.
A further objective is the provision of a Wurster dry powder coating process which applies polymer at a faster rate to the substrate due to the higher amount of polymer in the suspension or solution.
A further objective is the provision of a Wurster dry powder coating process which applies polymer at a faster rate due to the greater efficiency and efficacy of applying the glidant as a dry powder to reduce aggregation.
Another objective of the invention is to remove the suspended solids (inactive excipients such as talc, disintegrant such as crospovidone, nutritional additives such as probiotics, API's such as Fexofenadine and any material) from the suspension or solution, thereby removing sedimentation and clogging in the lines and spray gun of a Wurster coater.
Another objective (same as p. 1 re provision of a Wurster . . . ) which applies disintegrants as a dry powder directly to the substrate without the disintegrant being hydrated.
Another objective of the present invention is the provision of a Wurster processor with improved sprayability, reduced process time, and reduced solution instability of certain pharmaceutical and other polymers containing insoluble solids and or soluble solids.
Still another objective of the present invention is the provision of a Wurster coating apparatus which applies solids without needing to suspend or solubilize the solids so as to improve the process, reduce time and avoid instability of the solids with water or other solvents.
These and other objectives will become apparent from the following description of the invention.